JP2007229799A - Cooling grid equipment for continuous casting and method for producing continuously cast slab - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide cooling grid equipment for a continuous casting machine where the supporting area of a slab is sufficiently secured, and simultaneously, cooling capacity for a slab is improved. <P>SOLUTION: In the cooling grid equipment 6 for a continuous casting machine installed directly below a mold in a continuous casting machine, wear plates 14 in which the contact length (L)in the slab width direction with a slab per wafer plate is ≤40 mm are arranged in such a manner that the length of a gap between the wear plates adjoining to the casting direction is higher than the length of a gap between the wear plates adjoining in the slab width direction, and also, each oval type spray nozzle 15 is installed in the gap between the wear plates. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling grid facility for supporting and cooling a slab installed immediately below a mold of a continuous casting machine, and a slab manufacturing method using the continuous casting machine in which the cooling grid facility is installed. Is.

  In continuous casting of steel, molten steel poured from a ladle into a tundish is poured into a water-cooled mold through an immersion nozzle installed at the bottom of the tundish, and then the solidified shell formed by the mold is used. The cast slab as the outer shell is continuously drawn below the mold while being cooled, and a continuous cast slab is manufactured. In this case, first, in the mold, the molten steel is cooled by contacting the mold to form a solidified shell. Thereafter, the slab that has passed through the mold is pulled out in the casting direction by a pinch roll while being supported by a slab support / guide device including a guide roll, a cooling grid, a cooling plate, and the like. By being supported by the slab support / guide device, swelling of the slab in the thickness direction (referred to as “bulging”) is prevented. This slab support / guide device includes a spray nozzle such as a water spray nozzle or an air mist spray nozzle (hereinafter simply referred to as “spray nozzle” means both a water spray nozzle and an air mist spray nozzle). The slab is pulled out while being cooled by the cooling water sprayed from the spray nozzle, and eventually solidification to the center is completed. Then, it cut | disconnects to predetermined length with the slab cutting machine installed in the machine end of the continuous casting machine, and a continuous casting slab is manufactured.

  By the way, in recent years, in order to reduce the manufacturing cost, improvement in productivity has been demanded more than ever before, and in the continuous casting process, the speed of the manufacturing line, that is, the casting speed has been increased. In order to realize this high casting speed, it is necessary to solve various problems. In particular, a technique for more efficiently cooling and supporting the slab directly under the mold is required. Under high-speed casting, the thickness of the solidified shell immediately below the mold becomes thin, and this solidified shell breaks and breakout occurs, or the solidified shell does not break. Due to the pressure, bulging occurs, and the molten steel surface in the mold fluctuates up and down, and mold powder is caught in the solidified shell, resulting in problems such as quality defects. That is, there is a need for a method for efficiently cooling a slab directly under the mold while supporting a slab having a thin solidified shell thickness so that bulging does not occur.

  Conventionally, methods for supporting a slab directly under a mold are roughly classified into three types: a roll method, a cooling plate method, and a cooling grid method (see, for example, Non-Patent Document 1).

  In the roll method, a spray nozzle is installed in a gap between adjacent rolls in the casting direction, and the slab is supported by the roll while cooling the slab with cooling water sprayed from the spray nozzle. In this case, from the standpoint of cooling the slab, it is desirable to increase the roll diameter to increase the roll interval and widen the area of the slab that is water-cooled. Since it spreads, there is a problem that it becomes easy to bulge. Moreover, since the roll and the slab are in line contact, there is also a basic problem that the slab support area is small compared to the other two methods of supporting by the surface.

  In the cooling plate method, the entire width of the slab is supported by a single plate, and this plate has a water cooling structure in which a flow path for cooling water is formed. In addition to indirectly cooling the piece, it also has a function of directly cooling the slab by ejecting water from the surface of the plate toward the slab. Thus, in the cooling plate method, the entire width direction of the slab is supported by one large plate, which is a very effective method for preventing bulging of the slab, but the area for directly cooling the slab is small. Since it is small, there is a problem that the cooling efficiency of the slab is poor. Also, when a breakout occurs, there is no escape point for the steam generated after the water sprayed from the plate surface cools the slab, so there is a high risk of a steam explosion, which is also safe for operation. There is also a problem. Furthermore, since the plate is large and has an integral structure, it is also a big problem that processing and repair are difficult (see, for example, Patent Document 1).

The cooling grid system consists of a wear plate for direct contact with and supporting the slab, a back frame for supporting the wear plate, and a spray nozzle installed in the gap between the wear plates. A large number of wear plates support the slab, and the slab is directly cooled by cooling water sprayed from a large number of spray nozzles, ensuring a support area of the slab and simultaneously cooling the slab directly. It is the equipment which has both of ensuring the area of (for example, refer patent document 2 and patent document 3).
JP-A-57-25268 Japanese Patent Laid-Open No. 2002-120054 Japanese Utility Model Publication No. 6-23647 Miyoshi et al., Iron and Steel, Vol.60 (1974) No.7.p.860-867

  However, a careful examination of conventional cooling grid type equipment revealed that the conventional cooling grid equipment has the following problems.

  That is, in the conventional cooling grid equipment, the slab is cooled mainly by cooling water sprayed from a spray nozzle installed in the gap between adjacent wear plates, and the wear plate for supporting the slab. The cooling water is not directly applied to the contact part between the slab and the slab, and the cooling capacity of this part is weak, and the cooling capacity of the entire cooling grid equipment is insufficient at the time of high-speed casting required at present. This is because the wear plate itself is not a water cooling structure, but is cooled by spray water sprayed from a spray nozzle installed in the gap of the wear plate, and the contact portion between the slab and the wear plate is indirectly cooled by the wear plate. Because it becomes.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to ensure a sufficient support area of the slab when the slab support just below the mold is carried out by the cooling grid method, and at the same time, It is to provide a cooling grid facility for a continuous casting machine with improved cooling capacity, and to provide a method for producing a continuous cast slab using a continuous casting machine equipped with this cooling grid facility.

  The present inventors have intensively studied and studied in order to solve the above problems. The results of the examination and research are explained below.

  One way to increase the cooling capacity of the cooling grid equipment is to reduce the area ratio of the wear plate in the total area of the cooling grid equipment and to increase the area ratio directly cooled by the spray water sprayed. It is done. However, the area ratio of the wear plate in the total area of the cooling grid equipment is about 20% to 60%. From the viewpoint of stably supporting the slab, this area ratio can be greatly reduced from the current level. Have difficulty. Therefore, in the present invention, as a means for increasing the cooling capacity of the cooling grid equipment, the cooling capacity of the portion directly cooled by the spray is improved, and at the same time, the indirect cooling by the wear plate at the contact portion between the slab and the wear plate is improved. Considered to plan.

  The wear plate is usually made of cast steel or cast iron, has a flat plate shape with a flat contact surface with the slab, is cooled by cooling water sprayed from a spray nozzle, and is a slab in contact with the wear plate. Is not cooled directly by the cooling water but is indirectly cooled via the wear plate. Accordingly, it has been found that indirect cooling by the wear plate is required to be enhanced in order to further increase the cooling capacity in the cooling grid facility.

  Therefore, the mechanism of slab cooling by wear plate was examined. As a result, it was found that the cooling water supplied from the spray nozzle was applied to both side surfaces of the wear plate on the slab width direction side, the wear plate was cooled, and the slab was cooled by the cooled wear plate. That is, it has been found that increasing the specific surface area of both side surfaces of the wear plate on the slab width direction side to promote the cooling of the wear plate is effective in promoting the cooling of the slab by the wear plate.

  Based on the results of this study, we manufactured an experimental device that simulates the structure of a cooling grid facility that combines a wear plate and a spray nozzle. In this experimental device, we used a wear plate that was narrower than the conventional wear plate. The shape and arrangement of the nozzle and the shape of the spray nozzle were changed, and an experiment was conducted to cool the heated steel material using this simulated cooling grid equipment, and the cooling capacity under each condition was comparatively evaluated.

  FIG. 1 shows a schematic diagram of an example of a cooling grid facility used in the experiment. 1A is a front view seen from the slab side, and FIG. 1B is a schematic cross-sectional view taken along arrow X-X ′ in FIG. In addition, although the wear plate 14 shown in FIG. 1 is a vertically long octagon and is ship bottom shape, it is not restricted to this, It can be set as various shapes.

  In the experiment, the contact length (W) in the slab width direction with the slab of the wear plate 14 was changed, and the gap between adjacent wear plates was changed. In addition, as a spray nozzle for cooling the gap between adjacent wear plates, an oval spray nozzle that sprays cooling water in an elliptical shape and a full cone spray nozzle that sprays cooling water in a conical shape were compared. . FIG. 1 shows an example in which an oval type spray nozzle 15 is arranged as a spray nozzle, and a spray surface sprayed from the spray nozzle is denoted by reference numeral 16.

  The steel material for cooling was heated for about 1 hour in an electric furnace maintained at 1200 ° C., and then the steel material was taken out and fixed to an experimental apparatus to start cooling. During cooling, the temperature change of the steel material was measured with a thermocouple embedded in the steel material. And this temperature measurement value was read with the personal computer, and the heat transfer coefficient in the steel material surface was calculated in combination with the numerical calculation (details of the experimental method will be described later in Example 1).

  As a result, the contact length (W) between the slab and the wear plate in the slab width direction is 40 mm or less, that is, the width of the portion of the wear plate that contacts the slab is 40 mm or less. A cooling grid is constructed using narrow wear plates, and the gaps between these wear plates are made longer in the casting direction than the slab width direction, and the cooling water spray impingement surface is placed in the wear plate gap. It was found that the cooling ability was excellent when an oval spray nozzle having an elliptical shape was arranged.

  This is because, when the width in the slab width direction of the portion in contact with the slab of the wear plate is 40 mm or less, the specific surface area of both side surfaces on the slab width direction side of the wear plate increases, and the wear plate itself is cooled. This is because the cooling of the slab at the portion in contact with the wear plate is also promoted. On the other hand, when the width in the slab width direction of the portion in contact with the slab of the wear plate exceeds 40 mm, the specific surface area of both side surfaces on the slab width direction side of the wear plate is reduced, and the wear plate itself is cooled. It was found that cooling of the slab was not accelerated.

  That is, in the cooling grid facility shown in FIG. 1, the wear plate 14 having a contact length (W) with a slab in the slab width direction of 40 mm or less is used, and the gap between adjacent wear plates is larger than that in the slab width direction. A conventional arrangement in which a full cone type spray nozzle is installed by arranging a staggered arrangement so as to form a long rectangle in the casting direction and arranging an oval type spray nozzle 15 for spraying spray water in an elliptical shape in accordance with the gap shape. It was found that the heat transfer rate was significantly improved compared to the cooling grid equipment, and the cooling capacity of the slab in the cooling grid equipment could be enhanced. In general cooling grid equipment, the gap between the wear plates is a square having approximately the same length in the slab width direction and the casting direction, and the installed spray nozzle is a full cone type that sprays cooling water in a conical shape. A spray nozzle is arranged.

  The present invention has been made on the basis of the above examination results, and the cooling grid equipment for a continuous casting machine according to the first invention is a cooling grid equipment for a continuous casting machine installed immediately below the mold of the continuous casting machine. The wear plate whose contact length in the slab width direction with the slab per wear plate is 40 mm or less is adjacent to the wear direction in the casting direction rather than the gap length between the wear plates adjacent in the slab width direction. The gap length between the plates is arranged to be larger, and the oval type spray nozzle is installed in the gap between the wear plates.

  A method for producing a continuous cast slab according to the second invention uses the continuous caster provided with the cooling grid equipment for the continuous caster according to the first invention, and sprays cooling water from an oval type spray nozzle. Then, the slab is cast while being cooled.

  According to the cooling grid equipment for a continuous casting machine according to the present invention having the above-described configuration, the slab can be reliably supported, and at the same time, the cooling of the slab can be improved, even under high-speed casting conditions. It is possible to stably cast a high-quality slab without causing operational trouble, and an industrially beneficial effect is brought about.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 2 is a diagram showing an embodiment of the present invention, and is a schematic diagram of a continuous casting machine equipped with a cooling grid facility according to the present invention. FIG. 3 is an enlarged perspective view of the cooling grid facility in FIG. .

  As shown in FIG. 2, the continuous casting machine 1 is provided with a mold 5 for cooling and solidifying the molten steel 10 to form an outer shell shape of the slab 11. A tundish 2 for relaying and supplying molten steel 10 supplied from a ladle (not shown) to the mold 5 is installed. A sliding nozzle 3 for adjusting the flow rate of the molten steel 10 injected from the tundish 2 into the mold 5 is installed at the bottom of the tundish 2, and the molten steel 10 is injected into the mold 5 at the lower surface of the sliding nozzle 3. An immersion nozzle 4 made of a refractory material is installed.

  On the other hand, below the mold 5, a cooling grid facility 6 is installed immediately below the mold 5, and below the cooling grid facility 6, a plurality of opposed slab support rolls 7 are installed. The cooling grid equipment 6 and the slab support roll 7 are slab support / guide devices for guiding the slab 11 pulled out from the mold 5 while guiding the slab 11 downward. A pinch roll (not shown) for pulling out is included. A spray nozzle (not shown) such as a water spray nozzle or an air mist spray nozzle is disposed in the gap between the slab support rolls 7 adjacent in the casting direction, and the slab is cooled by cooling water sprayed from these spray nozzles. 11 is cooled while being pulled out.

  A plurality of transport rolls 8 for transporting the cast slab 11 is installed on the downstream side of the slab support roll 7. Above the transport roll 8, the cast slab 11 to be cast is provided. A slab cutting machine 9 for cutting a slab 11a having a predetermined length is disposed.

  As shown in FIG. 3, the cooling grid facility 6 is adjacent to a large number of wear plates 14 arranged in a staggered manner for supporting the slab 11 and a back frame (not shown) that supports the wear plates 14. And an oval type spray nozzle 15 installed in the gap of the wear plate 14. In FIG. 3, the cooling grid facility 6 is shown only in a part in the width direction of the slab 11, but the cooling grid facility 6 is installed over the entire width of the slab 11.

  The wear plate 14 needs to have a contact length (W) in the slab width direction with the slab 11 of 40 mm or less. The contact portion between the slab 11 and the wear plate 14 is indirect cooling by the wear plate 14. When the contact length (W) exceeds 40 mm, the wear plate itself does not cool as described above, and the slab This is because the cooling of the contact portion between 11 and wear plate 14 is not promoted.

  The wear plate 14 may be made of cast steel or cast iron. The wear plate 14 has a rectangular shape as shown in FIG. 3, while the wear plate 14 shown in FIG. 1 has a vertically long octagonal shape and has a ship bottom shape. Any shape can be used as long as it satisfies one requirement.

  That is, (1) the contact length (W) between the wear plate 14 and the slab in the slab width direction is 40 mm or less, and (2) cooling water or scale is not deposited in the gap between the wear plate 14 and below. (3) The support ratio of the slab 11 by the wear plate 14 is 20 to 60%, and other parts can be cooled by the oval type spray nozzle 15. .

  Further, the contact length (L) in the casting direction between the wear plate 14 and the slab 11 may be any number as long as it is larger than the contact length (W) in the slab width direction. In order to make the rectangle longer in the casting direction than in the slab width direction, it is preferable that the contact length (L) is not less than three times the contact length (W). That is, it is preferable that the shape of the wear plate 14 is such that the contact length (L) in the casting direction is at least three times the contact length (W) in the slab width direction.

  Such wear plates 14 are arranged such that the gap length between wear plates adjacent in the casting direction is larger than the gap length between wear plates adjacent in the slab width direction. Then, an oval type spray nozzle 15 having an elliptical spray surface is arranged in accordance with the shape of the gap between the wear plates. Since the oval type spray nozzle 15 can increase the dynamic pressure when colliding with the slab surface of the cooling water as compared with the full cone type spray nozzle, the slab 11 can be used even if the water density of the cooling water is the same. Can enhance the cooling. Here, the form of the oval type spray nozzle 15 may be either a water spray nozzle or an air mist spray nozzle.

  In selecting the oval type spray nozzle 15, the spray shape is first considered in consideration of the distance from the tip of the oval type spray nozzle 15 to the slab surface so that the spray range of the cooling water covers the area of the wear plate gap. To decide. Furthermore, from the viewpoint of preventing clogging of the oval type spray nozzle 15 due to foreign matter suspended in the cooling water, it is desirable that the foreign matter passage diameter of the spray nozzle be 1.5 mm or more. In particular, if the wear plate 14 is arranged in the width direction of the slab and the width of the wear plate gap is made too narrow, only the small oval spray nozzle 15 can be installed. May occur. Therefore, it is important to design the cooling grid equipment 6 in consideration of both the arrangement of the wear plates 14 and the selection of the oval type spray nozzle 15. Note that the foreign substance passage diameter is not the diameter of the spray nozzle at the tip of the spray nozzle, but the distance between the nozzle wall and the baffle plate installed inside the nozzle in the cross section of the flow path in the spray nozzle. It is a value represented by the interval between the narrowing positions.

  Further, the installation length of the cooling grid facility 6 in the casting direction is not particularly limited, and may be any number as long as at least the wear plates 14 are arranged in a staggered manner in the casting direction. However, since the cooling grid equipment 6 is originally a device that supports the slab 11 directly under the mold, a length of 3 m or more is not required.

  Using the continuous casting machine 1 having such a configuration, the molten steel 10 staying in the tundish 2 is injected into the mold 5 through the immersion nozzle 4 while adjusting the flow rate by the sliding nozzle 3. The molten steel 10 injected into the mold 5 is cooled in contact with the mold 5 to form a solidified shell 12. While maintaining the molten steel surface position in the mold 5 at a substantially constant position, the slab 11 having the surface as the solidified shell 12 and the inside as the unsolidified phase 13 is continuously drawn below the mold 5 to continuously cast the molten steel 10. carry out. The slab 11 from which the mold 5 has been drawn is cooled while being supported by the cooling grid equipment 6 and the slab support roll 7, and eventually solidifies completely to the inside. The cast slab 11 is cut by a slab cutting machine 9 to produce a slab 11a having a predetermined length. The spray amount of the cooling water from the spray nozzle installed in the gap between the slab support rolls 7 is not particularly specified, and an optimum range is appropriately set according to the steel type to be cast and the casting speed.

  By cooling the slab 11 using the cooling grid equipment 6 having the above configuration, the cooling strength of both the portion cooled by the oval type spray nozzle 15 and the portion cooled indirectly by the wear plate 14 is improved. Therefore, it can cool efficiently, supporting the slab 11 stably, and the production amount can be increased by increasing the casting speed. In addition, the difference in cooling strength between the portion cooled by the oval type spray nozzle 15 and the portion cooled indirectly by the wear plate 14 is reduced, and the cooling non-uniformity in the cooling grid equipment 6 is improved. It is also possible to prevent surface cracks of the slab 11 due to non-uniform cooling.

  An experimental device that simulates the structure of a cooling grid facility directly under the mold, combining a wear plate and a water spray nozzle, is manufactured, and in this experimental device, an experiment that simulates the cooling grid facility according to the present invention and the conventional cooling grid facility Using the equipment, the heated steel was cooled, and the cooling capacity was compared and evaluated. As a method for laboratory evaluation of the cooling capacity, a method is generally used in which water is sprayed on the heated steel material to cool it, and the heat transfer coefficient is obtained from the temperature history of the steel material. A hole was provided on the side opposite to the surface to be cooled, a thermocouple was embedded therein, and the temperature history was measured with the thermocouple.

  In the experiment, as shown in FIG. 4, an experimental apparatus having a combination of six oval water spray nozzles and six wear plates was used. The heated steel material was brought into contact with the wear plate, and the steel material was cooled by jetting cooling water from an oval water spray nozzle. FIG. 4 is a schematic diagram of an experimental apparatus for comparing and evaluating the cooling capacity of the cooling grid equipment.

  As an experimental apparatus simulating the cooling grid equipment according to the present invention, as shown in FIG. 4, an experimental apparatus simulating the above-described cooling grid equipment shown in FIG. 1 was prepared. That is, the longitudinally long octagonal ship-bottom wear plate 14 is arranged in two rows in the slab width direction and in the casting direction so that the gap in the slab width direction of the wear plate 14 is 45 mm and the gap in the casting direction is 90 mm. Three-stage staggered arrangement was made, and oval water spray nozzles 15 were arranged in these gaps. The width of the bottom of the wear plate 14 (the portion in contact with the slab) is 25 mm at the maximum.

  On the other hand, as an experimental apparatus simulating a conventional cooling grid facility, rectangular wear plates are arranged in two rows in the slab width direction so that the wear plate gap is 90 mm in both the slab width direction and the casting direction. Three-stage staggered arrangement was made in the casting direction, and full cone type water spray nozzles were arranged in the gaps. In this case, the width of the portion where the wear plate contacts the slab is 50 mm.

  The steel material used for heating is carbon steel having a width of 400 mm, a height of 600 mm, a thickness of 20 mm, and a carbon concentration of 0.2% by mass. On the surface opposite to the cooling surface of this steel material, a diameter of 1.8 mm, Nineteen holes with a depth of 18 mm were made, and a K-type sheathed thermocouple with a diameter of 1.6 mm was embedded therein. As shown in FIG. 4, the thermocouple is embedded at a total of 19 locations including the wear plate gap and the wear plate contact portion. The distance between the nozzle tip and the steel material was 80 mm for both the oval type water spray nozzle and the full cone type water spray nozzle.

  In the experiment, the above steel material was heated for about 1 hour in an electric furnace maintained at 1200 ° C., the uniformly heated steel material was taken out and fixed to the experimental apparatus, and cooling was started. During the cooling of the steel material, 19 temperature measurement values by a thermocouple were taken into a personal computer every 0.1 second. After the experiment, the measured temperature history and numerical calculation are combined to calculate the heat transfer coefficient (local heat transfer coefficient) at each thermocouple position, and the area average value of the obtained local heat transfer coefficient is used as the cooling grid. The cooling capacity of the equipment was evaluated.

  The test was conducted at the following two levels.

Level 1: The test was performed using an experimental apparatus simulating a conventional cooling grid facility, and the amount of cooling water per full cone water spray nozzle was 25 liters / minute. In this case, the water density of the cooling water in the gap between the wear plates is 3090 liters / minute · m ² . Here, the amount density of the cooling water in the gap between the wear plates is a value obtained by gradually reducing the flow rate per minute of the cooling water ejected from one spray nozzle by the area of the wear plate gap. The area of the wear plate gap is defined as “wear plate gap area = (gap length of wear plates adjacent in the slab width direction) × (gap length of wear plates adjacent in the casting direction)”. Hereinafter, level 1 is referred to as “conventional example”.

Level 2: A test was performed using an experimental apparatus simulating a cooling grid facility according to the present invention, with the amount of cooling water per oval water spray nozzle being 12 liters / minute. In this case, the density of the cooling water in the gap between the wear plates is 2960 liters / minute · m ² , which is almost the same as the conventional example. Hereinafter, level 2 is referred to as “example of the present invention”.

  Table 1 shows the average heat transfer coefficient of the cooling grid equipment measured at these two levels when the steel surface temperature is 850 ° C. Here, the average heat transfer coefficient is obtained by calculating the local heat transfer coefficient at the thermocouple installation position shown in FIG.

As shown in Table 1, the average heat transfer coefficient of the cooling grid facility in the conventional example was 1500 kcal / m ² · hr · K. In contrast, in the example of the present invention, the average heat transfer coefficient of the cooling grid equipment is 1860 kcal / m ² · hr · K, and the water density of the cooling water in the wear plate gap is almost equal to that of the conventional example. Regardless, it was confirmed that the cooling efficiency was improved by about 24% compared to the conventional example.

It is the schematic which shows an example of the cooling grid installation which concerns on this invention. It is the schematic of the continuous casting machine provided with the cooling grid installation which concerns on this invention. It is an expansion perspective view of the cooling grid equipment in FIG. It is the schematic of the experimental apparatus for comparing and evaluating the cooling capacity of a cooling grid installation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Continuous casting machine 2 Tundish 3 Sliding nozzle 4 Immersion nozzle 5 Mold 6 Cooling grid equipment 7 Casting piece support roll 8 Conveyance roll 9 Cast piece cutting machine 10 Molten steel 11 Cast piece 12 Solidified shell 13 Unsolidified phase 14 Wear plate 15 Oval type Spray nozzle 16 Spray surface

Claims (2)

  A cooling grid facility for a continuous casting machine installed immediately below a mold of a continuous casting machine, wherein a wear plate having a contact length in the width direction of the slab with a slab per wear plate of 40 mm or less is a slab The gap length between wear plates adjacent in the casting direction is larger than the gap length between wear plates adjacent in the width direction, and an oval spray nozzle is installed in the gap between wear plates. Cooling grid equipment for continuous casting machines.   A continuous casting machine comprising: a continuous casting machine comprising the cooling grid equipment for a continuous casting machine according to claim 1, wherein casting is performed while cooling the slab by spraying cooling water from an oval type spray nozzle. A manufacturing method of a piece.

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